JPS59119535A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high corrosion resistance, high output, a high S/N ratio and satisfactory traveling durability by forming a thin film of an amorphous alloy consisting of Ni and a specified amount of P on a magnetic layer. CONSTITUTION:A thin film of an amorphous magnetic alloy consisting of Ni and 12-20wt% P is formed on a Co-base magnetic layer made of Co or consisting of Co and Ni, Co and O, or Co, Ni and O. When the P content is <12wt%, the corrosion resistance reduces critically, and the electromagnetic transducing characteristics deteriorate. When the P content exceeds 20wt%, the corrosion resistance also reduces critically. The thin Ni-P film is in an amorphous state having no long-range regularity.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Background of the Invention Technical Field The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium having a continuous thin film type magnetic layer formed by a so-called oblique evaporation method.

Prior art and its problems As a magnetic recording medium for video, audio, etc., magnetic recording media (σ) having a continuous thin film type magnetic layer have been actively developed due to their compactness when rolled and rolled. Float.

Due to its characteristics, the magnetic layer of such a continuous thin film type medium is made of CO1Co-Ni%C0, which is formed by a so-called oblique evaporation method in which evaporation is performed at a predetermined angle to the normal to the substrate.
-0, Co-Ni-U based vapor deposited films are most suitable.

However, this magnetic layer has the disadvantage of being highly oxidizable and lacking in corrosion resistance.

Under these circumstances, various proposals have been made regarding protection layers 1- to be provided on such magnetic layers to improve corrosion resistance.

However, when a protective layer is provided, the spacing loss due to the protection layer increases, resulting in a decrease in electromagnetic characteristics and a decrease in output and S/N ratio. Also, with some protective layers.

The adhesive strength with the magnetic layer is low, the running friction is large, and there are problems with running durability.

Therefore, in a medium having an obliquely deposited magnetic layer as described above, a retaining layer that has high corrosion resistance, high output and S/N ratio, and high durability has not yet been found.

■ Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and the main purpose of the present invention is to provide a magnetic recording medium that has high corrosion resistance, high output, high S/N ratio, and good running durability. The goal is to provide a medium.

Such objects are achieved by the invention described below.

That is, the present invention has a magnetic layer containing Go or CO and 1 to 3 of Ni, Cr, and O on a substrate, and a P-containing lid of 12 to 20% by weight on this magnetic layer. This is a magnetic recording medium characterized by having a thin film of an amorphous alloy made of Ni and P.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The magnetic recording medium of the present invention has a magnetic layer on a substrate.

The magnetic layer contains CO as an essential component, and includes CO1Co+Ni,
It consists of Co + 0 or Co + Ni.

That is, it may consist of Co alone, or it may consist of CO and Nj. When Co + Ni, C
The weight ratio of o/Ni is preferably 1.5 or less.

Furthermore, in addition to CO or co-)-Ni, 0 may be included. When 0 is included, more favorable results are obtained in terms of electromagnetic conversion characteristics and running durability.

In such a case, the atomic ratio of 0/Co (if Ni is not included) or O/(Co+Ni) is 0.2
Below, it is especially preferable that it is 0.01-0.1.

On the other hand, the magnetic layer contains Co, Co + Ni,
In addition to Co + 0 or Go + Ni + 0, Cr
When combined, even more favorable results are obtained.

This is because electromagnetic conversion characteristics are improved, output and S/N ratio are improved, and film strength is further improved.

In such a case, Cr/(Co+Ni) c)
The weight ratio is preferably o,ooi to 0,1.

In this case, Cr/Co or Cr/(Co+Ni
) is 0.005 to 0.05 to obtain even more preferable results.

Note that such a magnetic layer may contain other trace components, particularly transition elements such as Fe, Mn, and V.

Zr, Nb, Ta%Zn, Ti, Mo, W,
It may also contain Cu or the like.

Such a magnetic layer is preferably an aggregate of grains having a columnar crystal structure tilted with respect to the normal to the main surface of the substrate. This improves electromagnetic conversion characteristics.

In such a case, each grain of columnar crystal structure is preferably inclined within a range of 30' or more with respect to the normal to the principal surface of the substrate.

Further, each columnar crystal grain usually has a length that spans the entire thickness direction of the first magnetic layer, and its short axis generally ranges from 50 to 50 mm.
It is said to be around 0A.

Then, Co and Ni added as necessary.

Cr etc. are components of this columnar crystal itself, and O
When added, 0 usually exists mainly in the form of oxide on the surface of each columnar crystal grain.

Such a magnetic layer is usually formed to have a thickness of 0.05 to 0.5 μm, more preferably 0.07 to 0.3 μm.

In this case, the magnetic layer may be provided directly on the substrate, or may be provided on the substrate via an underlayer.

Furthermore, although the magnetic layer is usually formed as a single layer,
In some cases, it may be formed by laminating multiple layers with an interlayer interposed.

Such a magnetic layer is usually formed by an oblique deposition method.

As the oblique evaporation method used, a known oblique evaporation method may be used, and the minimum value of the incident angle with respect to the normal to the substrate is preferably 30° or more.

The vapor deposition conditions, post-treatment method, etc. are as described in 1. There are various known methods of treating the waste.

A thin film of an amorphous magnetic alloy made of Ni and P is formed on such a magnetic layer.

In this case, the P content in NiP should be 12-20% by weight.

If the P content is less than 12%, the corrosion resistance will be critically reduced and the electromagnetic conversion characteristics will also deteriorate.
%, the corrosion resistance will be critically reduced.

This Ni P N film is in an amorphous state with substantially no long-range regularity.

Note that the thickness of the NiP thin film is 50 to 500A.

More preferably, it is about 100 to 300A.

Such a NiP thin film is formed by sputtering, so-called vertical evaporation, ion beam noting, or the like.

In this case, the deposition conditions may be in accordance with known conditions.

There are no particular restrictions on the substrate used, but a particularly flexible substrate, particularly one made of resin such as polyester or polyimide, is preferred.

Moreover, although the thickness may be one layer, it is particularly preferable that it is 5 to 20 μm.

A surface mark on the back surface of the magnetic layer forming surface is preferable.

This improves electromagnetic conversion characteristics.

In the medium of the present invention having such a structure, if necessary, a top layer made of various organic and inorganic materials may be further formed on the NiP thin film.

(2) Specific effects of the invention The magnetic recording medium of the present invention is useful as a magnetic recording medium for video, audio, and the like.

According to the present invention, corrosion resistance such as oxidation resistance and moisture resistance is extremely high.

Moreover, the electromagnetic conversion characteristics are improved, and the NiP film improves the output and S/N ratio.

Furthermore, the running friction is low and the running speed is also good.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

Example Co/Ni weight ratio 40CoNi alloy and Co
/Ni/Cr weight ratio 75/2015
A magnetic layer was formed to a thickness of 0.2 μm on a polyethylene terephthalate (PET) film containing NiCr and Cr and having a thickness of 10 μm using an oblique evaporation method.
o and Bo were produced.

The incident angle in oblique evaporation was 45°, and the evaporation atmosphere was as follows:
PAr=2×1O-2Pa, POQ=1×1O-2Pa
And so.

The obtained magnetic layers both have the corresponding alloy composition,
Both had a ratio of 0/(Co + Ni) = 0.03 (atomic ratio), and were inclined at about 35° with respect to the normal to the main surface of the substrate. It was an aggregate of columnar crystal grains that had grown over the entire thickness direction with a minor axis of 100A.

In addition, when performing Auger spectroscopy analysis while performing ion milling, it was found that Go was small near the surface, and 0 was chemically shifted, and there was a profile in which there was a lot of 0 near the surface. It was confirmed that it exists in a combined state.

Next, on the AO and BO magnetic layers, ' N
After forming an iP thin film, samples A□~A7 and 81~
I got B7.

In this case, the sputtering is PA,=2×1O−1P
It was carried out under the atmosphere of a. N formed in this way
The thickness of the iP thin film was 0.03 μm, and the P content in NiP was as shown in Table 1. Moreover, although samples A4 to A6 and 84 to B6 were amorphous, the other samples were aggregates of columnar crystal particles.

Each of these samples Ao-A7 and B. -For B7,
The following measurements were performed.

1) Corrosion resistance After being left at 60° C. and 90% relative humidity for 7 days, the change in magnetic flux per 1 d of sample was measured using a moving magnetometer (Hmax = 500 QOC).

2) Electromagnetic conversion characteristics Commercially available 1-F'e, 0. With videotape as standard,
Output was measured as recording/reproducing characteristics at 4.5MH2K. In this case, a ferrite head with a 0.3μ inertia gap was used. These results are shown in Table 1.
Shown below.

From the results shown in Table 1, the effects of the present invention are clear.

Note that samples A4 to A6 and 84 to B6 had low running friction and sufficient running durability.

Applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Agent Patent Attorney Yo Ishii -

Claims (1)

[Claims] 1. Co or eo and KNi on a substrate. It has a magnetic layer containing 1 to 3 of Cr and 0, and Ni and P with a P content of 12 to 20% by weight are formed on this magnetic layer.
1. A magnetic recording medium comprising a thin film of an amorphous metal alloy comprising: 2. The magnetic layer contains Ni, and the Go/Ni weight ratio is 1.
．． The magnetic recording medium according to claim 1, wherein the magnetic recording medium is 5 or more. 31, the magnetic layer contains Cr/(Co or co
The magnetic recording medium according to claim 1 or 2, wherein the weight ratio of +Ni) is 0.001 to 0.1. 4, magnetic no includes 0, 0/(Co or Co-
4. The magnetic recording medium according to claim 1, wherein the atomic ratio of 1-Ni) is 0.2 or less. 5. The magnetic recording medium according to any one of claims 1 to 4, wherein the magnetic layer is an aggregate of grains with a columnar crystal structure tilted with respect to the normal to the substrate. 6. The magnetic recording medium according to any one of claims 1 to 5, wherein the magnetic layer has a thickness of 0105 to 5 μm. 7. The magnetic recording medium according to any one of claims 1 to 6, wherein the thin film has a thickness of 50 to 500 Å.